$pdo->query($sql)

<?php
header("content-type:text/html;charset=utf-8");
try {
    $pdo = new PDO('mysql:host=localhost;dbname=test', 'root', '');
    $sql = "select * from user where id>3;";
    $stmt = $pdo->query($sql);
    var_dump($stmt);
    /*
     * object(PDOStatement)[2]
  public 'queryString' => string 'select * from user where id>3;' (length=30)
     *如果错的返回false
    */
    echo "<hr/>";
    foreach ($stmt as $row) {
        //var_dump($row);
        echo "编号:" . $row['id'] . "<br/>";
        echo "用户名:" . $row['username'] . "<br/>";
        echo "邮箱:" . $row['email'] . "<br/>";
        echo "<hr/>";
    }

} catch (PDOException $e) {
    echo $e->getMessage();
}

?>

Paste_Image.png

添加

<?php
header("content-type:text/html;charset=utf-8");
try {
    $pdo = new PDO('mysql:host=localhost;dbname=test', 'root', '');
    $sql = 'INSERT user(username,password,email) VALUES("king17","' . md5('king11') . '","imooc@qq.com")';
    $pdo->query($sql);
    $stmt = $pdo->query($sql);
    var_dump($stmt);//boolean false

} catch (PDOException $e) {
    echo $e->getMessage();
}
?>